The objective of this research is to elucidate the secondary structure and tertiary structural interactions of naturally occurring RNAs, and to study the nature of protein-nucleic acid interactions. Specific experiments include combined relaxation kinetic and NMR measurements on several RNA species, including tRNA, tRNA mutants, precursor tRNA and ribosomal RNA. The mechanism of thermal unfolding will be determined in these materials, thereby permitting conclusions about conformation and conformational stability. Experiments on protein-nucleic acid interactions will focus on questions such as the size of dNA helix occupied by a bound protein, whether the base pairs open when a protein is bound, and the site of interaction of specific proteins with single stranded RNAs.